Hello! After careful evaluation of your description of the agony you have, it does not appear to be of cardiac origin. I would have repeatedly taken a series of your ECGs by myself, & this itself would have been enough to exclude the diagnosis of ischemic heart disease
However it is surely what is known as 'Cervical Rib
Syndrome' from your description of the symptoms.
There is no point in having X-Ray, because the first type of the cervical rib syndrome which is completely bony, although visible in an X-Ray, does not cause any symptoms.
It is the second type, 'Fibrous cervical rib' which is responsible for your symptoms & the definitive way to manage it is decompression by operating the extra fibrous rib.
Thanks & wishing you a successful treatment!